Constant temperature maintenance system



Dec. 5, 1950 E. G. WHITE 2,532,382

CQNSTANT TEMPERATURE MAINTENANCE SYSTEM Filed NOV. 5, 1945 4 Sheets-Sheet l QZ' QI.

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Dec. 5, 1950 E. G. WHITE 2,532,382

CONSTANT TEMPERATURE MAINTENANCE SYSTEM Filed Nov. 5, 1945 4 Sheets-Sheet 2 Dec. 5, 1950 E. G. WHITE CONSTANT TEMPERATURE MAINTENANCE SYSTEM Filed Nov. 5l 1945 4 Sheets-Sheet 3 l Ed l `\1 Q14 Z 6; 1% W (-$3) I 6 l Y@ l 1&6. B* @mdf ATTE! R N EYS Dec. 5, 1950 E. G. WHITE 2,532,382

CONSTANT TEMPRATURE MAINTENANCE SYSTEM Filed Nov. 5, 1945 4 Sheets-Sheet 4 Patented Dec. 5, 1950 v CONSTANT TEMPERATURE MAINTENANCE v SYSTEM Edgar Guy White, Peru, Ill., assigner to Sampsel Time Control, Inc., Spring Valley, Ill., a corporation of Illinois Application November 5, 1945, Serial No. 626,606

6 Claims.

This invention relates to control devices and particularly to automatic means for perception of temperature operating range whereby to main tain a heat reserve at a central plant within limits to accord with transient weather conditions.

With conventional types of automatically fired heating plants there has been no reliable means known which would prevent overheating (or overshooting as it is sometimes called) of the heating media following long heat demands such as is incident to sharp temperature fluctuation. Various practices to overcome this condition of overrunning the heating cycle have been proposed but because the control factors required too constant attention to admit of proper regulation, certain benets of automatic operation have thereby become lost or ineffectual during critical conditions which obtain at seasonal temperature fluctuation.

It is the object of this invention to provide a means of automatic mean temperature change perception and to modify heat regulation extremities so as to maintain a constant desired heating temperature. The heat reserve controlling device being a temperature responsive member is located in the bonnet or boiler head of the heating medium. A thermostat is used to control directly the heat source, whereby not only to operate a heating medium, but also to regulate the reserve temperature limiting device located in the heating medium.

The invention will be better understood from the following detailed description thereof with reference to the accompanying drawings, in which:

Figure 1 is a side elevational view of a thermostat with the cover thereof in section such as may be used in an embodiment of the invention;

Figure 2 is a front elevational view of the unit featured in Fig. 1 with the cover transversely in section;

Figure 3 is a fragmentary sectional view taken approximately on the line 3 3 of Figure l;

Figure itis a fragmentary sectional view on the line 4-4 of Figure 1;

Figure 5 is a vertical sectional view similar to Fig. 1 but taken on a line approximately through the center of Fig. 2;

Figure 6 is a transverse sectional view through the temperature control apparatus and bonnet immersion attachment thereof featuring the clutch and Variable limit control which is used in an embodiment of the invention;

Figure 7 is a front view of the apparatus shown in Figure 6 with the cover in section;

Figure 8 is a fragmentary detailed sectional piece '12.

2 View through the magnetic clutch elements thereof;

Figure 9 is a schematic diagram of a temperature control system embodying the invention with the control and contact elements in their related positions;

Figure 10 is a circuit diagram similar to Figure 9 featuring a condition of change when the room has reached the desired temperature;

Figure 11 is a similar diagram featuring a condition when the room has reached a point above the desired temperature, and

Figure 12 is the same diagram under conditions when the room reaches the desired temperature and the system is re-set.

Referring more in detail to the drawing, and especially to Figures l to 5 inclusive, the numeral designates a room thermostat having an insulated base 22 and a snap-on cover 23 which may be frictionally retained.

The thermostat employs a bi-metal blade 24 secured at its upper end to an insulated block 26, Figs. 1 and 5, by means of the screw 28 and at its lower end carries an iron or steel abutment The block 25 is supported upon the plate and secured to the brackets 32 and 34, Fig. 5, by screws 33, the brackets 32 being secured to the base 22 in any well known manner. The

bracket 34 engages the inside of the cover 24' and threadably supports the stem 36 of the con^V trol knob 38, which is radially graduated in terms of temperature degrees.

The blades 24 and 34 are electrically connected to the terminal 40 by the wire 42 and the former is adjusted to aiiord any temperature response desired by rotating insulation knob 38 which ap-` plies or releases pressure on the blade 24 by withdrawing or extending the stem 36 which engages the blade 24, as shown in Figs. 1 and 5. Upon a slight rise in temperature, the blade 24 deflects to move the contact 44 thereon out of engagement with the contact 46 mounted on the base 22 and into engagement with the Contact Ell on the pivoted arm 52 which is pivotally mounted at 54 in the oppositely disposed ears 56 of the bracket 32. Upon a further rise in temperature the blade 24 applies pressure outwardly moving the arm 52 bodily and thus disengaging the contact 58 carried thereby from the Contact 60 secured to the base 22. Upon drop of 1 F.

switch 6D is again engaged by the contact 58, the contact 44 remaining in engagement with the contact until an additional drop of 1 F. disengages the aforementioned contacts and reengages the contact 44 with back contact 46.

Blade 24 and arm 52 are detentecl by the poles of permanent horse-shoe magnets 52 and 64 respectively, which in turn are secured to the base 22 by fastener t3.

The arm 52 comprises two brass pieces 6e and 68 respectively, which are pivoted, as previously described, and as they form a part of the electrical circuit, they are secured to an insulated strip and being spaced, as shown, are insulated from each other. Steel members l2 and 'lll are riveted on the ends of the blade 2d and arm 52 respectively, to provide magnetically attractive material for detenting. v

The brass piece .55 of the arm 52 is electrically connected at its upper end by the wire with the terminal 1S, the contact 135 to the terminal Bil by the wire S2. The brass piece G8 of the arm 52 is electrically connected at its upper end by the wire 84 with the terminal 35 and the Contact 6B with the terminal 8S by the wire Si).

Referring more particularly to Figures 6, l and 8, wherein is shown an improved clutch and variable limit control unit 9E which comprises the base 9a having the insert tube E@ secured to the base 94 and a cover @c frictionally engaging the rimof the base 94. The housing 9S is provided with the semi-spherical flange ilc which is secured to the furnace bonnet of heat supplying means lZ by screws it, retaining the semicircular bracket |535 in engagement with the sleeve |95, the plate it being interposed between the bracket Ide and the furnace bonnet oi heat supplying means lot. |The friction for the control being applied by the use of two magnets lit and H2 respectively, which are secured to the upturned ears lill of the brass top plate llc by screwsl H8. The plate HG is xed on the bushingY |20 and the circular plate m2 is loosely mounted on the bushing E29 intermediate the plate H6 and the collar |23 secured to the bushing H2B by screw lZl. The plate H6 carries an arm i2@ secured thereto by screws 26. rEhe arm |24 is movable between contacts 28 and ESQ, when the plate H6 is coupled to the plate |2 by the permanent magnets il@ and H2. The magnets app-ly a yieldable force to rotate the arm 52d between the contacts l28 and Hill which are mounted on the insulated plate |35 in response to temperature changes acting on the `loi-metal helix |32 one end of which is welded to the interior of the housing s at itil and the other ond of which is secured to the shaft E35 by a kscrew |38. Thus, action of the helix 532 is transmitted by the shaft i3d to the plate lie. Leads M2 and Mld, respectively, connect the arm lli and contacts |28 and E39 to the terminals let, i553 and |50, and thereafter to the leads 52, i5@ and |56.

Referring now in detail to Figures 9, 10, il and 12, the terminal It@ is connected to terminal |58 and 'ESQ of relay coil to2 by lead |66. Terminal 8e of the thermostat 2li is connected through secondary winding lll of a transformer and Contact pair 58-6@ to terminal l5@ of control 92 and tor terminal |66 of relay V|532 by leads |55 and |68. Terminal 'ill of the thermostat 26 is connected to terminal |45 of the control 92 by lead |52, and to contacter 24. Terminal Stof thermostat 2o is connected to terminal |50 of control 92 by lead |55. Y'.ierminals Ile and lle of relay m2 close the circuit of stolrer motor, oil burner, or motorized valve |78.

The function of the thermostat 2E! is as follows: Upon rise of temperature in the space to be heated, the oi-metal blade Il@ deects in direction indicated by arrow H Figure 9, until the temperature for which it is adjusted has been reached. At this point, the contact fle-,draws away from back contact i6 and engages instead front contact 5t. Upon further rise of temperature mem- -ber 'H3 is pivoted aboutits trunnion screws tl until contact 58 of conductor plate 22 draws away from itsl pole contact til. This opens the circuit Fig. 9, which had been energizing relay The function of the friction driven temperature limit control is as follows Upon rise of bonnet or boiler head temperature, the contact arm |24 oscillates counterclockwise, 9, contacting terminal 53E. Contact arm lfi, upon contacting terminal 36, is thereby physically prevented from moving further. rhe magnetic friction coupling then slips until the heater reserve temperature ceases to rise. Upon drop of temperature, arm l2@ leaves terminal i3d and contacts terminal E28. The same type of coupling behavior then occurs until the reserve heat temperature ceases to drop.

The function of relay lt is as follows: a heat calling circuit is completed by thermostat 28, the winding of relay E62 is energized over lines it and E68 as already described causing both its armatures to draw up. rlhis establishes a holding circuit over line H2 and an operating circuit for the fuel motor H8. mains energized holdingrelay closed until the contacts 58 and ttl of thermostat 2|! come agar.

The control knob of thermostat Z is set to the temperature desired in the space to be heated. If the ambient temperature is lower than this setting, lblade 2li will assume-a condition as shown in Figure 9 closing the already described circuit which energizes relay let'. As a consequence there areestablished its own holding circuit and the fuel motor operating circuit. Continued operation Of the fuel-motor will build up a heat reserve in the furnace or boiler, untilV a predatormined increase in heat reserve is achieved whereupon the arm |2i of control 92 will draw away from contact |23 and engage instead contact |30.

The magnetic friction drive will permit the arm |24 to slip after it'has contacted terminal 39 until the reserve temperature ceases to rise. Eventually the space will become heated and the` bi-metal blade 24 of the thermostat will move in the direction of arrow H. Since blade 24 is magnetically attracted by its associated horseshoe magnet 62 iniluencing said blade in a leftward direction, Fig. 9, untilthe heating.` effect on its bi-metallic structure sets up sumcient counterforce to draw away from its magnet 52, it will be understood that when such force eventually -becomes adequate to overcome the magnetic effect and move the blade rightwardly, such force will necessarily be of sufficient magnitude to thrust contact of blade 2d physically into engagement with the front contact 5t. Thiswill establish an energizing circuit for magnet E62 subject to' completion when contactor l2d of unit 92 engages its left contact point ll-ZSLas during interim low heat reserve conditions in the furnace or boiler with which unit $32 is associated. The stated operatingv circuit formagnet H42 is traceable from the left hand terminal of secondary winding I'H through terminal 80.1ine lt. terminal IZB, contactor |215. line |52, terminal 18, front contact 50, contact All including blade ,24. terminal M, line |64. terminal |60, winding of magnet |62. terminal |611?, line |.f8,'terminal MH. line 56, current limiting resistor |18', terminal 86, contats 58 and 66, terminal 88, to the other end of When The locking circuit re` the secondary winding lll. The aforedescribed condition is illustrated in the schematic circuit of Fig. 12 and in accordance therewith magnet |62 will remain energized so long as the bonnet or boiler temperature remains low, causing the nring apparatus to endeavor to raise the temperature to a range within the established angular manifestation of contactor |24.

If under the aforedescribed conditions, the reserve heat temperature is signiiicantly lowered to cause shaft |36 and the magnetic clutch elements H5, ||2, and |22, to slip as the contacter |24 encounters adjustable screw of terminal 52%, a change will be wrought upon the previously established temperature range condition in the unit 92. Eventually, however, the reserve heat temperature will rise through the efforts of the heating apparatus represented by the fuel motor |18 until the contactor |24 will draw away from its left hand contact terminal |28, opening the aforedescribed circuit and deenergizing relay HB2 because at this time the relay lockingv circuit described above will be found open at contacts 58-69 of the heat demand thermostat Zd by reason of the action of blade 24 pressing upon contact 58 with suiiicient force to draw member 'lil away from its magnet E2. 1f, however', the ambient temperature of thermostat 2@ meanwhile falls so as to permit contacts 58 and 63 to close, the holding circuit for relay |52 will remain closed, relay |62 will continue energized, the firing of the furnace or boiler will continue until the locking circuit is opened at contacts '5B- 60.

It is to be understood, therefore, that so long as no heat demands are made by the unit the immersion thermostat 92 will maintain a heat level in the bonnet or boiler corresponding to the angular fluctuation range of contacter iZ between contact |28 and contact li, The frictional characteristic of the clutch in thermostat 92 permits this temperature range to he automatically displaced within a wider overall temperature range according to prevailing weather conditions. Thus during mild temperature conditions the reserve heat range level may be tained at. for example. between 120 145 F. During more severe or colder seasonal conditions the reserve temperature range may be advanced to fluctuate between 189 and 295 F. This displacement will occur notably as an. automatic response to changes in general temperature conditions and without the intervention ci human agency regardless of whether the ambient temperature conditions rise or fall as a result of weather change.

It is apparent that if a definite ratio of ded-ection between the bi-metal of the thermostat and the temperature responsive member ci the triction driven temperature limit control is esta??- lished, i. e., assuming a 15 change in means s pplying heating medium temperature will permit 1/2" change in temperature in the space to he heated., then with a temperature responsive member which will move the contact arm 25 from the terminal |39 to the termina-l 28, or vice versa, on a change means supplying heating medium temperature, it is obvious that the temperature in the space to be heated will be held within 1/2 temperature variation.

In the use of a day-night thermostat, where the temperature is lowered at a desired time at night and must be brought again to the desired temperature in the morning, there will be an excess of heat, or overshooting, in the iirst cycle.

This condition is corrected in this manner: Because of the excess heat, or overshooting, the bimetal blade |24 will deect in the direction of arrow H opening contacts 88 and 80. For example: If it requires 1/2" to cause the bi-metal to deflect sufciently to open the terminals S8 and Sii above the iirst stage (or condition in which terminals 88 and 80 are closed), then working backwards, this 1/2o corresponds to a 15 excess temperature in the heating medium. And, since terminals 88 and 83 are open, means supplying heating medium is inoperative until the 12 temperature change has occurred in the space to be heated, permitting the bi-metal blade |24 to return to the first position, i. e., terminals 88 and 88 and terminals 4@ and 86 closed. During this period or" time, the temperature change in the heating medium has preceded the temperature change in the space to be heated. Thus, contact arm |24 of control 92 moves to contact |28 which prevents it from moving any further, allowing the friction driven temperature limit control to slip, setting the position of contact arm |24 at a lower operating temperature than the nrst setting which resulted in the overshooting. Terminals SS and 8? of the thermostat 20 closing simultaneously with terminals fs@ and 86 of the thermostat 20, the means supplying heating medium will be energized, causing temperature in said means to rise until terminal arm |24 of control 92 (actuated by heating medium at means of supply)` contacts terminal |28. This shunts the relay coil :ie-energizing the relay permitting contacts |19 and |53 and |74 and |16 to open, stopping the means supplying heating medium.

The heat generating medium is now being entirely controlled by the control 92. If a furnaceor boiler temperature change of 15 (or'less) must be held to maintain a room temperature not varying more than 1/2", then a differential of 10 between terminals 4Q and 78 will keep the temperature in the space being heated within 1K2", at the setting which the thermostat has just effected. Should there be a demand for more heat because of external influences (or otherwise) bi-metal blade 24 will deilect in the direction of arrow M closing the circuit through terminals 4S and '18. This opens the relay deenergizing circuit so that the rising heating medium temperature which has caused contact arm |24 to contact terminai I3@ of the control 92 means supplying heating medium will continue to operate, re-setting contact arm |24 to a higher temperature demand, until bi-metal blade 24 is satisfied, defleoting in the direction of arrow H opening the circuit through terminals 40 and 'I8 of the thermostat 20, and closing circuit through the terminals fill and 88 of the thermostat through arm |24 and contact I3@ of the control 92. This de-energizes the relay coil |62 and opens means supplying heating medium circuit.

The foregoing specications with the accompanying drawings are presented for the purpose of describing and illustrating the broad principles of this invention, and as various modifications are possible without departing from the spirit of the invention, it is to be understood that the invention is not restricted by reason of the specific construction or application disclosed, or otherwise than by the appended claims.

I claim:

1. In an automatic heating system, an electrically operated heat generating apparatus, a thermostatic device having a thermal element disposed in a heat reserve storage space of said 1 apparatus including.Y a pair of' oppesitely placed. electrical contacts, a. contacter movable between and alternatively engageable with said pair of oppositely placedcontacts, a friction coupling between said thermal element and said movable contacter, a room thermostat comprising a heat responsive contacter movable between a stationary heat calling contact and a floating heat satiety contact, a shifta-bl'e member in said room thermostat carrying electrically insulated one from another said heat satiety Contact and a locking circuit contact, a stationary contacting point cooperating with said locking circuit contact, detent means ier influencing said shiftable member to present its carried locking circuit contact into engagement with said locking circuit stationary contact, an electric relay controlling a heat generating apparatus contact and a. selflocking contact, and an energizing circuit for said relay including. in circuit communication, said room thermostat heat calling contact, said room thermostat locking circuit contact, said locking circuit stationary contact, and a shunt path .for said relay including said` thermestatic device con taeter and one of its said pair of oppositely placed contacts for d'e-energizing said relay to arrest further operation of said heat generating appan ratus in response to a heat suii'iciency signal movement by said thermostatic device contacter, and a secondary energizing circuit for said relay including the other of said pair of eppesitely spaced contacts and the iloating heat satiety contact.

2. In an electrical control system for automatically fired heating plants, a roem thermostat having a bijmetallic member movable between heat calling and heat satiety contacts, primary circuit means electrically connected te said bimetallic memberl when in its said heat calling contact position for energizing an electric relay, an electric relay under control of said primary circuit means having a control armature for energizing a plant iiring apparatus and a locking armature for maintaining itself closed after its energization is initiated by said room thermostat mem-ber, la secondary member in said room `thermostat carrying a front contact for engagement with said binietallic member when the latter is in its said beat satiety contact position for prem paring a secondary energizatien circuit for said electric relay. and carrying an additional Contact in circuit with said electric relay, said secondary member beingV shiftable by movement of said bimetollic member in the direction of but beyond its heat satiety contact position whereby to cause said secondary member additional contact to open the locking circuit to said electric relay.

3. The combination set forth in claim 2, in-

. clnding a reserve heat thermostatic device having a thermal element and a contacter movable thereby between alternative contacting positions, a friction coupling between said thermal element and said movable contacter, and a contact engageable by said contacter for completing said secondary energization circuit for said electrical relay whereby to energize said relay for initiating said plant firing apparatus independently of the heat calling contact of said room thermostat and in response solely to reserve heat conditions.

4. In a heating control system. a room thermostat comprising a biased thermestatic contact element movable between a relay energizing call circuit Contact and a secondary arm contact, a

8'. biased secondary arm carrying electrically in sulated from each other, a bonnet thermostat contacter and a call circuit commen return contactor and movable in opposition .te its bias during overtravel of said room thermostat contact element away from a com-mon return circuit contact, a bonnet thermostat located in a heat reserve chamber of a heat generator having a thermostatically responsive contacter sli-p clutch coupled to its thermostatic element and electrically connected te said secondary arm bonnet thermostat contactor andmovable between a cool side call circuit making contact and a hot side relay shunt circuit contact, and an electromagnetic relay energizable by the call circuit when initiated by said room thermostat or when main-A tained by said bonnet thermostat for operating the heat generator and having a self-energizing lock contact pair for establishing a holding: circuit parallel to the call circuit of said roem thermostat contact element.

5'. The combinationy set forth in claim 4 including a shunt resistor in said calll circuity common return for relieving the short circuit lead when said bonnet thermostat contacter engages its. hot

side Contact te shunt and release said relay.

6. In a heating system control apparatus, a-

room thermostat, a bonnet thermostat, and a furnace operating relay, a magnetically biased contacter in said room thermostat movable between relay energizing and bonnet control contacts in response to cool and het ambient temperature roem conditions, respectively, a biased Contact lever in said room thermostat supporting a rst contact strip for electrical engagement by said biased contacter when the latter moves inte its bonnet control contact position in response te rising ambient tempera-ture room conditions and carrying a second Contact strip which engages during the normal or biased condition a commen return making contact, said biased contacter being movable in the direction of its bonnet centrol contact in response to overheat temperature conditions to overpewer the bias of said contact lever for opening its commen return making strip, a contacter in said bonnet thermostat frictionally articulated with its thermostat element and electrically connected to said first Contact strip, said bonnet contacter being movable between a relay energizing secondary circuit path contact which is alternative to said roorn thermestat relay energizing contact during low limit temperature bonnet conditions and a relay shunting Contact in parallel with a relay locking circuit during high limit temperature bonnet conditions.

EDGAR GUY WHITE.

REFERENCES Cll'llED The following references are of record in the ille of this patent:

UNITED STATES PATENTS Number Name Date 1,583,586 Fischer May 4, 1926 1,807,218 Hinnekins May 26, 1931 1,960,718 Standifer May 29, 1934 2,089 002 Beman Jan. 26, 1937 2,117,514 Shipley May 17, 1938 2,148,491 Moore Feb. 28, 1939 2,153,195 Lilja Apr. 4, 1939 2,154,352 Sargent July 4, 1939. 2 189 382 McGrath Feb. 6, 1940 2,219,441 Carnes Oct. 29, 1940 

